This invention relates to a head rest assembly and particularly to a head rest assembly which is mountable on the external rear surface of the backrest of a chair and the like.
A common head rest assembly for a chair and the like is built integrally into the backrest during the fabrication of the latter. The assembly requires openings to be provided both at the upper edge and within the body of the backrest to accommodate the assembly as well as mounting means within the backrest to support the assembly therein. Thus, it is complex in construction and it is difficult and time consuming to fabricate. Furthermore, it also complicates the finishing process of the backrest since the outside cover of the backrest must be provided after the head rest assembly has been properly mounted into the backrest. Moreover, such type of head rest assembly is difficult to incorporate into an existing backrest since it would require substantial alterations to be made in the construction of the backrest to accommodate the assembly.
The above drawbacks are alleviated with an externally mounted head rest assembly. The simplest externally mounted head rest assembly comprises a rectangular casing mounted onto the rear surface of the backrest. The casing has an upper slot opening and an aligned lower slot opening through which an elongated bar on the top end of which the head rest is mounted, may be slidably inserted therethrough. The elongated bar is then mounted at any selected upwardly extending position with a hand operated set screw or bolt provided in the front of the casing. The casing of such head rest commonly has a welded construction in which its rear cover is welded to its front cover. Such welded construction is again time consuming and expensive to carry out. Furthermore, the elongated bar is invariably marred by the set screw in use such that the bar surface has an unpleasing appearing and worse still sharp edges may be formed on the marred surface by the set screw, which may cause injury to the user such as cutting of fingers or hand when adjusting the bar.
Another type of known externally mounted head rest assembly is provided with a spring-loaded latch assembly within a casing such that the head rest mounting elongated bar may be slidably inserted therethrough in selected position by operating the latch assembly. The latch assembly of such head rest assembly heretofore has been provided by a somewhat S-shaped casting iron latch element formed by expensive and time consuming molding process. The latch element is normally biassed by a compression spring in a locked position to lock the head rest mounting elongated bar at a selected position, and it may be depressed to an opened position to allow the elongated bar to be adjusted to any chosen position. All components within the casing of such assembly require to be welded in place; accordingly, it is also expensive and time consuming to produce.